Plain English Meaning
A set of steps the pilot decides on before takeoff for how to stop the airplane on the runway if something goes wrong before lift-off. It covers when to make the stop decision, how to stop the aircraft, and what to do once stopped.
Full Definition
The pre-planned actions a pilot takes to safely stop an aircraft on the runway when continuing the takeoff is judged unsafe or impossible. These procedures specify the decision point before which a takeoff will be discontinued, the immediate actions to bring the aircraft to a stop (typically reducing power to idle, applying brakes, retracting flaps as appropriate, and maintaining directional control), and the follow-up steps after stopping (clearing the runway, notifying ATC, and inspecting the aircraft).
Context Anchor
Used during takeoff briefings, takeoff training, and any where the pilot must be ready to stop on the remaining runway.